There is a need for reducing fuel consumption required for a ship to carry out a voyage from a specified departure port to a specified destination port as much as possible under a condition that the ship can arrive at the destination port by a certain timing.
For example, JP2007-057499A is an example of a document that discloses a technique that meets the above-mentioned need. JP2007-057499A discloses a system that calculates, with regard to each section between neighboring nodes set in an area between a departure point and a destination point, a sailing speed, fuel consumption, etc. based on data sets indicating performance of a ship that sails from the departure point to the destination point and data sets indicating maritime weather conditions in the area, and searches the best sailing route from the departure point to the destination point based on the calculated sailing speeds, fuel consumption, etc. In JP2007-057499A, “the best sailing route” is defined as a sailing route that incurs the lowest cost calculated based on fuel consumption, sailing time, etc.
When a ship visits ports on a sailing route during a voyage, it is necessary to reserve in advance a time slot for using a berth at each port. This time slot is usually referred to as a “berth window,” and is frequently expressed as “B/W.” Usually, a ship operation manager or a ship agent who undertakes various operations at a port such as cargo handling operations on behalf of the ship operation manager applies to the relevant port authority for a desired berth window for a ship, and the port authority allocates a berth window to the ship in response to the application.
Once berth windows are allocated, a sailing time of each section of a sailing route between a port and its subsequent port is roughly determined. Once a sailing time of each section of a sailing route is determined, a sailing speed over each section of the sailing route is determined. Once a sailing speed over each section of a sailing route is determined, fuel consumption required for sailing each section of the sailing route is determined. Accordingly, total fuel consumption required for sailing the entire sailing route is affected by a berth window allocated to the ship at each port to be visited by the ship during a voyage.
Within an allocated berth window, a time period during which a ship is actually docked at a berth can be adjusted. For example, a ship may dock at a berth at a beginning time of an allocated berth window and leave the berth before an ending time of the berth window after all operations for the ship performed at the berth, such as cargo handling operations, are completed. Alternatively, a ship may dock at a berth later than a beginning time of an allocated berth window and leave the berth almost at an ending time of the berth window after all operations for the ship performed at the berth are completed. Sailing times of sections of a sailing route before and after the port differ between the former case and the latter case. Accordingly, total fuel consumption required for sailing the entire sailing route is also affected by a time period during which a ship is actually docked at a berth within an allocated berth window.
Therefore, if a ship operation manager, a ship's navigator or the like can know in advance a preferable time period of docking a ship at a berth that causes a reduction in total fuel consumption required for the entire sailing route, he/she can achieve a reduction in total fuel consumption by reserving a berth window covering the preferable time period, by shifting a time period during which a ship is actually docked at a berth within an allocated berth window so that the time period becomes close to the preferable time period, or by shifting an allocated berth window so that the allocated berth window covers the preferable time period.